1. Field of the Invention
This invention relates, in general, to hydraulic couplings, and specifically to hydraulic couplings used in undersea drilling and production applications. More particularly, the invention involves undersea hydraulic couplings having seal retainers that are engaged to the female coupling member.
2. Description of Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male member and a female member with seals to seal the junction between the male and female members. The female member generally has a cylindrical body with a relatively large diameter bore at one end and a relatively small diameter bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore contains the seals and receives the male portion of the coupling. The male member includes a probe section insertable into the large bore of the female member. According to various embodiments of the device, the seals either abut the end, or face, of the male member or engage the male member about its outer circumference. Hydraulic fluid is then free to flow through the female and male portions of the coupling and seals prevent that flow from escaping about the joints of the coupling.
Optionally, a check valve may be installed in the female member and also in the male member. Each check valve is open when the coupling is made up; however, each check valve closes when the coupling is broken so as to prevent fluid from leaking out of the system of which the coupling is part.
In U.S. Pat. Nos. 4,694,859 and 5,762,106 to Robert E. Smith III, an undersea hydraulic coupling and metal seal is disclosed. A reusable metal seal engages the circumference of the probe when it is positioned within the female member body. The seal is held in place by a cylindrical seal retainer. When the male and female portions of the coupling are parted under pressure, the seal retainer prevents the metal seal from blowing out through the bore of the female member.
U.S. Pat. Nos. 4,900,071 and 5,052,439 to Robert E. Smith III disclose an undersea hydraulic coupling with an elastomeric seal that is restrained from radial movement into the central bore of the female member by a circumferential shoulder on one or both surfaces adjacent the seal. Preferably, the seal has a dovetail interfit with one or both surfaces. U.S. Pat. Nos. 5,099,882, 5,203,374, 5,232,021 to Robert E. Smith III also show undersea hydraulic couplings with these seals. An inner cylindrical surface of the annular seal engages the circumference of the male member or probe as the probe is inserted into the female member. As the male member or probe is pulled out of the female member bore, the leading face of the male member reaches the soft annular seal intermediate that bore. When the face reaches the midpoint of the soft annular seal, the dovetail interfit prevents the seal being imploded into the bore, as the seawater and/or hydraulic fluid enter the bore at high pressure.
To retain one or more seals in the female member of an undersea hydraulic coupling, a seal retainer may be attached to the female member. The seal retainer may be a generally sleeve-shaped cylindrical body that is inserted into the bore of the female member until the seal retainer abuts a shoulder in the bore of female member. To secure the seal retainer against the shoulder, a retainer locking member may also be attached to the female member using threads or snap rings, for example. A radial seal may be retained between the seal retainer and retainer locking member. Additionally, one or more face seals may be positioned between the seal retainer and shoulder.
In subsea drilling and production applications, a small gap may exist between the seal retainer and internal shoulder of female subsea hydraulic coupling members. This gap may exist as a result of very high pressures and/or high temperatures at subsea depths, tending to loosen the seal retainers and/or retainer locking members. It can be difficult to overcome this problem and eliminate the gap by increasing the torque applied to the retainer locking member which secures and holds the seal retainer in abutment against the shoulder. As a result of the gap formed due to high temperatures and pressures at subsea depths, seals positioned in the female coupling member between the seal retainer and shoulder may extrude into and through the gap between those two components, causing leakage of hydraulic fluid from the coupling and/or seawater into the coupling. Accordingly, an undersea hydraulic coupling is needed having a seal retainer that reduces or eliminates any gap between the seal retainer and shoulder in the female coupling member.